In the field of endodontics, one of the most important and delicate procedures is that of cleaning or extirpating a diseased root canal to provide a properly dimensioned cavity while essentially maintaining the central axis of the canal for filling of the canal void and capping of the tooth. When done properly, this step enables substantially complete filling of the canal with biologically inert or restorative material without entrapping noxious tissue in the canal that could lead to failure of the therapy.
In a root canal procedure, the dentist removes diseased tissue and debris from the canal prior to filling the canal with a biologically inert or restorative filling material. Many tools and techniques have been designed in an effort to enable dentists to perform the difficult task of cleaning and shaping root canals. Historically, dentists have used endodontic files to remove the soft and hard tissues in and adjacent the root canal. These endodontic files are typically made by grinding helical flutes into a working portion of a small elongate tapered rod to create a curvilinear, abrasive file with a helical cutting edge.
Conventional endodontic instruments with helical cutting/abrading edges have certain endemic problems which, to some degree, have been tolerated and approached from a management perspective rather than an elimination perspective. For example, conventional endodontic instruments may only cut when rotated in one direction. Further, the instruments typically must be backed off after rotating in a first direction to unload the instrument before advancing the instrument further into the root canal. Conventional endodontic instruments also may begin to screw into the wall of the canal rather than continuing down the canal toward the apical tip of the root. In some cases, this “screwing in” can cause the instrument to break through the side of the root canal and into surrounding tissue or bone. Or, it may begin to “drift” or displace laterally relative to the center axis of the canal as it is moved roto-axially.
These and other problems continue to plague practitioners and designers alike in their efforts to enlarge and prepare for filling the varied tooth root canal configurations in a manner substantially concentric with the natural or original canal curvature/shape to enable successful, effective and permanent treatment therapies. Accordingly, there is a need for improved endodontic instrument designs and methods that will avoid, minimize or eliminate drawbacks and problems associated with conventional endodontic instruments including, but not limited to, “screwing in” issues and the inability to cut in more than one direction encountered during the use of conventional endodontic instruments.